Logging the data received from the dynamometer

On old-fashioned dynamometers, the operator or the observer had to manually record the simultaneous readings on paper. Nowadays, most dynamometers replace the observer’s notes with computerized devices that acquire and store the data. Because of the very loud noise generated by the dynamometer and the engine, a performance test is stressful to anyone who’s watching it. In these given conditions, it is very difficult to manually record all the data. A reliable computerized data acquisition system is considered to be indispensable today among engine builders and testers. Nowadays it is possible to buy recording, control, and playback capabilities in a palm sized package, that many years ago would have cost a lot more and would have had the size of a refrigerator. An appropriate computerized data acquisition system must have a very fast sampling rate. For obtaining quality data, you will need at least 100 samples, of all sensor channels, per second (100Hz). A 200Hz logging rate or more is even better. It is important to remember that between spark plug firings there is a drop in torque and rpm that can be measured. The crankshaft is accelerated right after combustion occurs and afterwards it slows down until the plug will fire one more time. It is not possible to detect these rapid highs and lows when you are driving on the track or on the road, but the dynamometer will. Therefore, a 200 Hz logging rate for your data acquisition system should do the trick, as well as an appropriate dynamometer. However, if you sample at only 50Hz, you should consider that you are recording a single torque and rpm sample every other revolution. From time to time, a series of samples will synchronize with the firings of the plugs, and sometimes the data samples will fall in synch with some lower power compression strokes. If you are using a fast and reliable acquisition system that read each cycle multiple times, then the data captured can be used to average out the given phenomenon. Averaging the data is a very important step in data acquisition. At this point, while experienced dynamometer operators see an identical power curve in both graphs, inexperienced dyno operators expect to see a smooth, clear line. The reason why the ability to average and dampen the data is essential for the acquisition system is that you don’t have to deal with so many printings. For instance, at 100Hz you're getting 1000 lines of data for even a ten-second dynamometer pull. You might choose not to search for any small changes in dozens of pages of data every time you want to prepare another run. Averaging both eliminates transient noise and produces clear printouts, and thus it is very useful in the process of logging the data from the dynamometer.

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Does dynamometer testing damage the car?

There is no actual proof that dynamometer testing might damage the car in any certain way.

While performing tests, dynos don’t interfere with the engines performance and more importantly, don’t do any damage to it.
Some of the things that may cause damage to engines are over-revving, excessive heating, shock loading or incorrect fuel or ignition settings.
If however your engine malfunctions after performing a dynamometer test, it’s almost certain that the testing, if properly done, wasn’t the cause of the damage.

It is more likely to damage your engine when you drive your car on the road than when you test it by the means of a dynamometer under controlled artificial conditions. You should always make sure that the dyno operator is a trained professional and that the dynamometer has an appropriate cooling system.
A 60 centimeter diameter fan is appropriate for a power run. It will prevent the vehicle from overheating.

However, you should keep in mind that dynamometer testing and setting up race cars and bikes require more controlled testing conditions. A bike or car that heats up after a few hours testing suffers from heat soak into the transmission, bodywork, engine block, oil, and so on. This interferes with the amount of power produced, and influences the accuracy and the objectivity of the performance test.
To make sure everything will go smoothly while performing your tests on engines, you actually need a wind tunnel in which you should manipulate your dynamometer. When you are driving on the road at full power there is a lot of fresh air that surrounds and cools the entire vehicle, and you should do your best to recreate some of these natural conditions when you perform your tests.

If your dynamometer or the place you go to in order to get your car or bike dyno tested does not have suitable working conditions or lacks an appropriate cooling system, it is not advised to perform any tests.
The problem concerning the damage done by dynamometers on the tires is more debatable. Tire manufacturers recommend dynamometer owners to replace tires after every test performed. They claim that the tires design is not intended for purposes like dynamometer testing and say that the heat or tire deformation could damage the interior structure. Due to these facts, they strongly recommend replacing the tires after testing.

However, this should be done more as a precaution, and if the tires are rather new, well designed dynamometers should not damage them. Just to make sure that everything is in order, remember to always check the tires condition after every test you perform.

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All The Things You Need To Know About Engine Dynamometers

The most professional devices that can measure an engine's power and torque are the engine dynamometers. They are used by the engine manufacturers themselves.

In order to perform the measurements on the engine (this is done before the engine in mounted into the chassis), the engine is connected to the dynamometer with a shaft. Afterwards, the engine is ignited, and it is set to run at a constant speed, and the torque that is applied to the dynamometer is exactly the engine's torque. The results of these measurements are quite accurate and there are no losses because of friction.

The new-generation dynamometers are connected to computers and they are very easy to handle and operate. They can almost perfectly simulate racing and normal driving conditions.
When driving on the road, there are a few factors that may modify the way an engine acts and the power it produces. Among these there's the air's temperature, level of humidity and also its pressure. These can be taken into consideration when testing an engine with a dynamometer, with the help of some formulas the power that an engine can give can be calculated under several types of meteorological conditions, so how the power modifies when the air pressure drops for example can be easily calculated.
Real-life conditions can be simulated by increasing the temperature at which the dynamometer tests are performed, because the engine is heating up as it runs.

Anyway, it mustn't be forgotten that once the engine is installed into the chassis it will connect to the drivetrain, and this plus a few more things will make an important part of the power to be absorbed, so the readings from an engine dynamometer will be a little different. To measure the power of the dynamometer 'at the wheels' a chassis dynamometer is required.

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